Scuse my ignorance here but I have read quite a bit about this device but have not got a handle on what exactly it is and how it works? Questions are; Is it automatic or manual, is it fed from the hot water supply, is it elctrical or what. Its just that I have seen posts about it not working cos the temp setting was wrong, white smoke, it effects fuel consumption etc. Is there any post that covers auxiliary heaters for dummys or can anyone fill me in!! Thanks for any help.